title: Extracellular nucleotide derivatives protect cardiomyocytes against hypoxic stress.
abstract: BACKGROUND
  Extracellular nucleotides have widespread effects and various cell responses. Whereas the effect of a purine nucleotide (ATP) and a pyrimidine nucleotide (UTP) on myocardial infarction has been examined, the role of different purine and pyrimidine nucleotides and nucleosides in cardioprotection against hypoxic stress has not been reported.
  
  
  OBJECTIVE
  To investigate the role of purine and pyrimidine nucleotides and nucleosides in protective effects in cardiomyocytes subjected to hypoxia.
  
  
  RESULTS
  Rat cultured cardiomyocytes were treated with various extracellular nucleotides and nucleosides, before or during hypoxic stress. The results revealed that GTP or CTP exhibit cardioprotective ability, as revealed by lactate dehydrogenase (LDH) release, by propidium iodide (PI) staining, by cell morphology, and by preserved mitochondrial activity. Pretreatment with various P2 antagonists (suramin, RB-2, or PPADS) did not abolish the cardioprotective effect of the nucleotides. Moreover, P2Y₂ -/- , P2Y₄ -/-, and P2Y₂ -/-/P2Y₄ -/- receptor knockouts mouse cardiomyocytes were significantly protected against hypoxic stress when treated with UTP. These results indicate that the protective effect is not mediated via those receptors. We found that a wide variety of triphosphate and diphosphate nucleotides (TTP, ITP, deoxyGTP, and GDP), provided significant cardioprotective effect. GMP, guanosine, and ribose phosphate provided no cardioprotective effect. Moreover, we observed that tri/di-phosphate alone assures cardioprotection. Treatment with extracellular nucleotides, or with tri/di-phosphate, administered under normoxic conditions or during hypoxic conditions, led to a decrease in reactive oxygen species production.
  
  
  CONCLUSIONS
  Extracellular tri/di-phosphates are apparently the molecule responsible for cardioprotection against hypoxic damage, probably by preventing free radicals formation.
authors.affiliation: Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
authors.forename: O
authors.initials: O
authors.lastname: Golan
authors.forename: Y
authors.initials: Y
authors.lastname: Issan
authors.forename: A
authors.initials: A
authors.lastname: Isak
authors.forename: J
authors.initials: J
authors.lastname: Leipziger
authors.forename: B
authors.initials: B
authors.lastname: Robaye
authors.forename: A
authors.initials: A
authors.lastname: Shainberg
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D015687:Cell Hypoxia; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D045604:Extracellular Fluid / Q000378:metabolism*; D055786:Gene Knockout Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D008929:Mitochondria, Heart / Q000502:physiology; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011684:Purine Nucleosides / Q000378:metabolism / Q000494:pharmacology*; D011685:Purine Nucleotides / Q000378:metabolism / Q000494:pharmacology*; D058914:Purinergic Antagonists / Q000494:pharmacology; D011741:Pyrimidine Nucleosides / Q000378:metabolism / Q000494:pharmacology*; D011742:Pyrimidine Nucleotides / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000235:genetics; D058473:Receptors, Purinergic P2Y2 / Q000235:genetics; D013312:Stress, Physiological; D014544:Uridine Triphosphate / Q000502:physiology
chemical_list: D000975:Antioxidants; D002614:Chelating Agents; D011684:Purine Nucleosides; D011685:Purine Nucleotides; D058914:Purinergic Antagonists; D011741:Pyrimidine Nucleosides; D011742:Pyrimidine Nucleotides; D017382:Reactive Oxygen Species; D018048:Receptors, Purinergic P2; D058473:Receptors, Purinergic P2Y2; C104749:purinoceptor P2Y4; D014544:Uridine Triphosphate